"No matter who the President is or what your politics, this behavior is not merely inappropriate for this (or any) event; it's juvenile & stupid, even deranged," writer Mark Tapson tweeted. "And yet it was met with a standing ovation. These snobs think this is somehow courageous."

It's not the first time De Niro has spoken out against Trump.

In January his speech at the National Board of Review Annual Awards Gala included a profanity-laced rand about the President.

"Our baby-in-chief -- the j***-off-in-chief, I call him -- has put the press under siege, ridiculing it and trying to discredit it through outrageous attacks and lies," De Niro said. ""This f***ing idiot is the President. It's 'The Emperor's New Clothes' -- the guy is a f***ing fool ... our baby-in-chief -- the 'J******-in-chief' I call him."

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